A variety of metal alloys are used for orthopaedic implants and are chosen on the basis of the high strength, ductility, fracture toughness, biocompatability, and corrosion resistance. It is generally known that the fatigue and corrosion properties of orthopedic implant devices fabricated from these alloys can be affected by different surface treatment processes including shot blasting. Recently, orthopaedic implant devices have been surface treated by shot blasting with alumina, in the form of aluminum oxide having a hard crystalline structure. Glass shot is also being used as a blasting medium as well as stainless steel shot. The problem with shot blasting orthopaedic components is that the blasted substances tend to become imbedded in and/or leave a residue on the surface of some alloys therefore requiring subsequent steps of glass bead blasting and electropolishing. Since the contamination by the blasting medium must be substantially removed, the depth of the cold worked outer layer formed by the blasting is limited. One method for increasing the depth of the cold worked outer layer is described and claimed in U.S. Pat. No. 5,057,108 issued on Oct. 15, 1991 entitled: METHOD OF SURFACE FINISHING ORTHOPEDIC IMPLANT DEVICES. As claimed, the '108 patent calls for the shot blasting of the outer surface with metal shot followed by blasting with a glass bead and electropolishing.
When porous surfaces, such as fiber metal mesh or metal beads, are either diffusion bonded or sintered to the body of an orthopaedic implant, it is known to use a carbon tool to hold pressure against the porous surface. The problem is that during the process, small pieces of carbon may become attached to the porous surface. This carbon must be cleaned off of the porous surface.